The present invention relates to a new and improved hydrostatic support member or element, particularly, although not exclusively, for use in rolling mills, and to a new and improved method of using the aforementioned hydrostatic support member.
In its more specific aspects the invention relates to a new and improved hydrostatic support member or element, particularly for use in rolling mills, which comprises a pressure chamber or space adapted to be supplied with a pressure fluid or pressurized fluid medium and at least one movable bearing shoe containing a bearing or running surface provided with at least one pressure pocket flow communicating with the pressure chamber by means of at least one throttle or throttling bore.
Such hydrostatic support elements are known, for example, from U.S. Pat. No. 3,802,044, granted Apr. 9, 1974, and U.S. Pat. No. 3,846,883, granted Nov. 12, 1974, and serve to mount or support movable, especially rotating members relative to a base member or foundation. Due to an axial mobility of the piston and an inclinability of the bearing shoes there can be attained an automatic adaptation of the bearing or running surface to movements of the counter surface and the formation of a constant gap between the two members, and thus, there can be obtained a constant supporting force between the two members within certain limits.
Typical methods of using such hydrostatic support members in rolling mills are described in, for example, U.S. Pat. No. 4,041,752, granted Aug. 16, 1977, U.S. Pat. No. 4,059,976, granted Nov. 29, 1977, and U.S. Pat. No. 4,218,905, granted Aug. 26, 1980. Thus, a web of a material, like, for example, a metal band, a plastic foil or a paper web, is passed between two working rolls pressed against each other and is rolled or smoothed. The working rolls are suppoed by support members of the aforementioned type in a pressing plane or laterally or transversely thereof. Additionally, back-up or supporting rolls can be provided which press against the working rolls and which also may be supported by hydrostatic support members.
Instead of achieving a supporting action by using support members acting from the outside, the supporting action also may be provided at a carrier or support provided within the roll by the use of support members which are also arranged within the roll as described, for example, in U.S. Pat. No. 3,949,455, granted Apr. 13, 1976.
Due to abrasion and wear as well as due to the periodically required regrinding of the working rolls and, to a lesser extent, also the back-up or supporting rolls, the roll diameter continuously decreases during the period of operation of the rolling mill. In metal rolling mills, for example, the decrease in diameter may amount to as much as 10% until an exchange and a renewal of the working rolls is required. At a diameter of 25 cm. of the working rolls the bearing shoes of the support members thus would not only have to be able to adapt to a change in the distance of the bearing surface from the roll surface of more than 1 cm. but also the bearing surface would have to retain a uniform distance from the roll surface throughout the entire region when the radius of curvature of the roll surface changes by 10%. The aforementioned support members were not able to effect such adaption and permitted only substantially smaller changes in the diameter until the center of the bearing or running surface would engage the roll surface due to the different curvature. During operation of a rolling mill the bearing shoes thus had to be frequently exchanged for others having a different radius of curvature or had to be adapted to the changed roll diameter.
Due to the deformation of the rolls during operation of the rolling mill the radius of curvature of the roll surface also changes, particularly when supported from the inside when the roll is structured as a roll shell. Also in this case support members or elements are desirable which permit some degree of variation in the radius of curvature.
Hydrostatic support members or elements already have been suggested, as, for example, by British Patent Application Publication No. 2,073,829, published Oct. 21, 1981 and U.S. Pat. No. 4,262,400, granted Apr. 21, 1981, the bearing surface of which is elastically deformable or is made of a flexible material. However, the deformation range of such support members is too small to be used in rolling mills. With greater deformations there result too large counter forces which do not permit a uniform bearing or support gap. The elastically deformable or flexible material is unsuited for the rough rolling mill operation, has too small a service life and causes frequent shut-downs due to operational disturbances.